Field of the Invention
This present invention relates generally to the fields of custom optics and the manufacture thereof. More specifically, the present invention relates to algorithms for implementing a custom correction (termed herein intelligent correction) and manufacturing custom ophthalmic optics that particularly optimizes the optical design of a wavefront guided correction that accounts for registration errors between the correction and the underlying wavefront error on the eye.
Description of the Related Art
Standard ophthalmic optics only allow for the correction of a small subset of optical defects in the human eye, namely sphere, cylinder and prism. These defects are easily corrected and their correction provides adequate visual performance in the vast majority of normal subjects. However, there are visual advantages to correcting additional defects in the eye. These advantages are particularly well seen when dealing with eyes that have elevated levels of optical defects that can occur, for example, naturally, as a result of disease or as a result of surgical intervention on the eye or trauma to the eye.
For example, higher order ocular aberrations can significantly impact visual performance. While these higher order aberrations can be easily quantified, current contact lens designs do not provide an intelligent design philosophy that allows for the minimization of these aberrations and optimization of visual performance on an individual basis. The current state of the art lacks sensitive deployed methods to determine the impact of resulting residual aberrations on visual performance that occur due to misalignment, termed registration uncertainty, of the wavefront guided correction with respect to the underlying wavefront error of the eye.
Particularly, perfect alignment between the wavefront error (WFE) of the eye and a wavefront guided correction (WGC) that is designed to perfectly correct all of the eyes' WFE will provide the visual system with the best possible image for all pupil diameters. Unfortunately, for a variety of reasons well known to the industry, perfect registration of the correction with the underlying WFE is rare, if ever, achieved. Even if the WFE and the WGC can be measured and constructed perfectly and depending on the complexity of the wavefront error and the resulting WGC, registration errors of an ideal WGC can lead to retinal images that are worse than no correction. Registration errors can be static, e.g., with an onlay, inlay, refractive surgery, or dynamic, e.g., with a contact lens.
For example, a wavefront guided soft contact lens (WGSCL) or a wavefront guided scleral lens (WGSL) can provide better retinal image quality (RIQ), (1-3) comfort and longer wear time than a traditional gas permeable corneal contact lens. However, for a WGSCL or WGSL to provide optimal and stable RIQ, the WFE to be corrected must be measure accurately, the corrections must be implemented correctly and the correction must be well registered with the eye's wavefront error. In practice, the contact lens must move a small amount to maintain good ocular health. Movement of the correction, even if made perfectly, with respect to the underlying wavefront error causes variable residual aberrations, which variably degrades RIQ. The magnitude and variance of RIQ degradation is dependent on the magnitude of the underlying wavefront error, the design of the correction and the amount the correction's registration error.
Assuming that contact lens movement on the eye is Gaussian in nature and selecting a portion of individual aberration terms to correct instead of correcting all the aberration terms, report methods to design a correction consisting of partial correction of every aberration term to minimize the average variance of the residual wave-front aberration produced by Gaussian decentrations (translations and rotations) are reported (4-5). In the approach introduced by Guirao et al optimization does not take into the account the visual impact resulting from the interactions between aberration terms (6). Nor does it capitalize on metrics of image quality known to have a high correlation with measures of visual performance such as acuity. Further, the assumption that the movement and rotation of a contact lens on the eye was Gaussian in nature is far from true. How a contact lens, regardless of its design translates and rotates is highly dependent on contact lens designs, i.e., sphere, truncated or prism ballasted, toric, size, etc., lid geometry and tear flow (7-8).
Thus, there is a need in the art for improvements in the design philosophy of customized optics and methods of manufacturing the same given noise in measurements and registration uncertainty. That is, there is a need to improve actual performance using a metric of optical quality that is highly correlated with gains and losses in visual performance. Specifically, the prior art is deficient in methods to optimize the optical design of a wavefront guided correction to provide a specific level of gain in visual performance, e.g., acuity, within a user defined variation in the visual performance measure of interest given the anticipated alignment errors of the delivery system and the associated errors in measurement. The present invention fulfills this long-standing need and desire in the art.